Chasewater Dam

The 200-year-old reservoir at the heart of Chasewater Country Park was drained of water in early 2010 amid concerns for the safety of the dam which dates back to 1797.

The £5.5 million project, started by Lichfield District Council was taken over by Staffordshire County Council in May 2011.

Now the ‘plug has gone back in’ and water levels can once more start to rise. This will restore Chasewater to its original position as a major regional leisure attraction, wildlife haven and key component of the Midlands canal network. Mark Winnington, Staffordshire County Council’s Cabinet Member for Environment and Assets said:

“This has been a major engineering project that has been carried through to a swift and successful conclusion.

“I am now delighted to be able to confirm that the plug is back in and the reservoir will start to refill naturally with water.”

The original role of the reservoir was to regulate water in the Midlands canal network – in times of drought water would be drawn from the reservoir to ensure the economically vital canals were still deep enough to navigate.

Fears however had grown that the earth dam was no longer safe to withstand major floods, was leaking, and could pose a danger to nearby homes.

County Councillor Winnington said: “We now have a much better understanding of the dam. Overflow precautions have been improved to safeguard nearby residents in the event of severe flooding, and we will be able to monitor the condition of the dam much more closely in the future.

“The drawdown culvert – the equivalent of the plughole in a bath – was located and inspected for the first time in over 200 years. Vital improvements have now been made. A mystery brick-built chamber that does not appear on any plans was also discovered inside the dam, and will now be used as part of our monitoring procedures.”

Water does seep through the dam, but this is perfectly normal and acceptable as long as it is carefully monitored to spot potential safety concerns. It has also created a mini-ecosystem that has become a Site of Special Scientific Interest. The work has ensured this is safeguarded.

Clive Thomson, the county council’s Head of Specialist Services said: “The dam is as safe as it is possible to make it and we will now be able to monitor its condition in far greater detail than was previously possible.

“Some water will always pass through an earth dam, but we are now able to keep a very close eye on how much and ensure this is not weakening the structure.”

County Councillor Winnington said: “People should start to see the water levels in the dam rise. We realise that many local people have been frustrated about the length of time that the reservoir has been empty, but we really have completed the work in as short a time as practical, and to keep local people informed with help from colleagues at Lichfield District Council.

“This work will provide reassurance for local people, will allow the country park to go from strength-to-strength as a visitor attraction and will also benefit wildlife and users of the regional canal network.”

It is hoped the reservoir should have refilled fully by Summer 2013 if there is average rainfall.

Some facts:

There has been a lot of activity and progress made since the last posting including carrying out the inspection of the original drawdown culvert which was drained and inspected during August. 

The results of the inspection showed the culvert to be in remarkably good condition and it has been agreed that no remedial works are necessary to the brickwork. 

An unrecorded chamber some 20 metres from the inlet was discovered during the inspection and the engineers have been considering how this asset can be utilised in the future management of the dam. 

In addition one of the main penstocks was found to be damaged and a formal inspection is being carried out by specialists this week.

Plans have been drawn up to make improvements at both the inlet and outlet of the drawdown culvert and works will commence shortly.

The installation of the filter drain at the base of the dam on the downstream side was completed during August and work is now well underway to re-grade the slope of the lower embankment and we are also installing additional gravel drains on the downstream slope to assist with future monitoring.

We will be taking the opportunity to improve the condition of certain areas of the front face of the dam and this is likely to be localised using materials already on site.

The overflow arrangements for the dam (Nine Foot Pool) have been completely redesigned and plans for an improved drawdown system which will be used at times of heavy rain have been drawn up. 

The construction sequence to complete these works is being looked at and works are on-going but it is likely that this will be the last part of the works to be completed.

We hope to be in a position shortly to announce when we anticipate the works will be complete and, critically, when the reservoir can start re-filling.

Our next update will be given when this information is available.

Staffs CC Team.

The main reason that Chasewater Reservoir exists is to provide a water supply into the canal system.

This water travels from the reservoir through a brickwork culvert which runs on the bed of the reservoir, under the eastern dam to the valve chamber and then out into the canal.

While we have the reservoir drawn down we are taking the opportunity to inspect the culvert and, if necessary, carry out any repairs.

However, the culvert is still under two metres of water, so to get access to it, we are building a sheet piled wall, or coffer dam, around the mouth of it, so that we can pump out this water and then clean out and repair the culvert. This dam is now almost complete as the photographs show. We will shortly start to pump out the water to see what we have got to deal with.

The work at the toe of the northern end of the eastern dam involves installing what is in effect a very big gravel filter drain, which will help to draw down and collect the water that seeps through the dam. This will allow dam engineers to monitor what is happening.

This part of the work is also now nearing completion and will be followed by the regrading of the lower slopes of the embankment because they are too steep in some places.

The works at the railway causeway (which are now complete) and at the Nine Foot Pool (which are now underway) are required because the original structures were not big enough to cope with the water that could be expected to flow through them during peak floods conditions, and which could have caused water to breach the dams.

The new structures will have much greater capacity to deal with high flood flows in the future.

The below photographs show the construction of end walls to the new weir in the Nine Foot Pool.

More updates soon.
Staffs CC Team

Completion of sheet piled cofferdam around the drawdown culvert

Completion of sheet-piled cofferdam at the drawdown culvert

Construction of end walls to new weir

Completion of final length of filter along dam

Completion of sheetpiling and filter along the back of the dam

Formwork completed, ready to concrete weir end-wall

Sorry this is a little late, here’ s a recent update. Thanks to you all for your patience:

• The installation of the toe drain to the northern end of the dam continues to progress well.
  The review of the works to the nine-foot pool has been completed to enable construction to restart in this area.
• During July a cofferdam will be installed in front of the inlet to the main reservoir drawdown culvert which will enable the culvert to be exposed, cleaned and inspected for damage. This will mean that no further water drawdown will be required in the reservoir, other than locally around the inlet.
• It is hoped that within two to three weeks our team (county council) and Galliford Try will know what remedial works are required to the drawdown culvert. This will help us to provide an indication of when the reservoir can start to refill.

Cheers

The county team

Here’s the update from the county team this week:

• The work behind the north embankment sheet piles is continuing and should be complete by early August.
• Reconstruction of the weir in the 9 Foot Pool will begin this week.
• Strimming of vegetation from the downstream face of the dam will be carried out shortly.
• With the scheme review progressing well, we are now working with Galliford Try and the Panel Engineer to finalise the details and programming for the completion of the outstanding works.

More next week.

Here’s the update from the county team this week:

• Review of scheme by panel engineer now well in hand
• Causeway works now substantially complete
• Excavation and placement of filter material behind the sheet piles continuing
• Works to start in the overflow pool area
• Finalising temporary work arrangements to enable draw down pipe to be inspected

More next week.

Here’s the update for this week from the county team:

• The sheet piling to the toe of the northern end of the embankment is complete.
• Excavation and placement of filter material behind the sheet piles will start this week along with the removal of the bog mats.
• The tops of the piles will then be trimmed to match the ground profile.
• Installation of additional silt curtains in the canal will commence this week.
• There are still some minor works outstanding at the causeway which will be completed over the next couple of weeks.
• The review of the remaining key elements of the works is progressing. 
    

Evening all,

Our colleagues at the county council have provided the following update on this week’s works: 

• The causeway works are now substantially complete. 
• Subject to Chasewater Railway carrying out internal safety checks tonight (27/5/11) it is hoped a full line operation will be in place over the bank holiday weekend. 
• Further details on www.chasewaterrailway.co.uk 
• Staffs County Council was formally registered by the Environment Agency as an undertaker of Chasewater Dam (along with British Waterways) on the 25 May  
• The county team appointed new ARPE and Supervising Engineer 
• A review of certain key elements of the works is being carried out by the county team. A new programme of works will be issued once review has been completed.  

A joint press release was issued today by Staffordshire County Council and Lichfield District Council:

Chasewater Country Park and its reservoir have been transferred to Staffordshire County Council in a strategic move set to secure and strengthen the long-term future of this key regional resource.

Chasewater Country Park is home to one of the largest reservoirs in the West Midlands and a country park that attracts around 150,000 visitors a year.

County Councillor Mark Winnington, Cabinet Member for Environment and Assets, said: “Chasewater Country Park consists of 360 hectares of open space, and is a fantastic fit for the county’s property portfolio.

“It will join our network of 12 country parks and open spaces which are run as leisure attractions and havens for wildlife.

“We are already looking at potential ways of developing Chasewater further as a cultural and economic facility. The county council operates the Chasewater Innovation Centre which has tremendous development potential. The site also lies very close to where the Staffordshire Hoard was discovered, and we are keen to work with our Mercian Trail partners to see what opportunities could exist for telling the story of this breathtaking piece of our local history at Chasewater.

“We are also keen to develop relations with all the many community groups that currently use Chasewater and seek their views on the site’s potential. This will include Chasewater Railway, the sailing club, wildlife group and other stakeholder groups. There is also the county council run Outdoor Education Centre that could benefit. We will look at all options to draw more people to the area and benefit the local economy.

“We will build on the good work Lichfield District Council has carried out up to this point.”

To date Chasewater Country Park and reservoir have been owned and managed by Lichfield District Council, which inherited the park in 1994 following a local authority boundary change. Since then, millions of pounds have been pumped into the park’s transformation, thanks to the work of the district and county council, together with external grant funding.

The reservoir provides British Waterways with essential water to maintain levels in the Birmingham Canal Network, and beyond. The reservoir is currently empty, as essential multi-million pound improvement works to the dam take place.

Councillor Val Richards, Deputy Leader of Lichfield District Council, explains: “It is most unusual for a small district council like ours to be responsible for managing such an integral part of the nation’s infrastructure. Managing an asset of this size places a huge burden on the district council and our small number of council tax payers. We are incredibly grateful to the team at Staffordshire County Council for working alongside us, and for agreeing to take over the future ownership and management of the park and dam.”

Under the move Chasewater Country Park will continue to be managed by a team at Lichfield District Council for the next three years and the county council will lead the completion of the essential improvement works to the dam.

Councillor Mark Winnington continued: “We have a broad range of skills within the county council that include complex engineering project management such as the dam improvements.

“Staffordshire County Council and Lichfield District Council are committed to ensuring that the public will continue to be able to enjoy the attractions of Chasewater in coming years, and that through the works to the dam, the safety of all those living nearby will be secured. There will be no additional costs to the tax payer as a result of the transfer, and once the works are complete local people and visitors will be able to enjoy Chasewater Country Park at its very best once again.”

Sorry we’ve been a bit quiet – with Easter, the Royal Wedding and last week’s elections, it’s been a bit busy at the DC. But we’re back now and here is our latest update.

Since the last update, we’ve progressed with the following:

• We’ve continued work at the causeway – the issues regarding levels and wingwalls now seem to have been addressed and we hope to get the railway back and running by the bank holiday.
• We’ve laid foundations and the culverts for the new bridge on the eastern dam the have been laid.
• The track has been laid to the toe of the dam and the piles have been moved to the toe, ahead of the arrival of the piling rig. We expect the rig to arrive later this week, and we hope that the piling can be completed in about 4-5 weeks.
• We will also be installing the silt curtains in the canal this week.

More soon … but here’s some photos:

Pool Road Bridge - new bridge

The culverts in the new Pool Road bridge